Tool holder for cutting bodies

ABSTRACT

Tool holder for cutting bodies ( 5 ), which may be mounted on a base holder ( 15 ) by means of a fixing device ( 41 ), and a stop, cooperating with the above, running in a planar embodiment in the direction of the tool holder. A positive positional fixing against any movement along the three axes of the spatial coordinate system may be obtained, whereby the planar embodied stop is divided into planar sections ( 19, 21 ), by means of a machined recess ( 23 ), between which the recess ( 23 ) forms a seat for housing a projecting matching body ( 25 ) on the base holder ( 15 ) and the walls of the recess ( 23 ) form support surfaces ( 31, 33 ) for the matching body ( 25 ) which each define differing planes, embodied in a planar manner perpendicular to the stop, such as to feed the displacement and torsional forces resulting from the cutting force into the matching body ( 25 ) of the base holder ( 15 ).

[0001] The invention relates to a tool holder for cutting bodies having the characteristics claimed in the preamble of claim 1.

[0002] DE 40 24 096 C2 discloses a tool holder having a cutting tool for metal cutting, a minicutter bar in particular, having a cutting insert braced by means of a clamping leg resting against it on a flat clamping surface in a recess having cutting insert mounting surfaces of a lengthwise slotted forked holder shaft. In the disclosed solution the clamping surface of the cutting insert is positioned in parallel with the axis of the holder shaft, the recess in the holder shaft having three cutting insert bearing surfaces, specifically, a bottom surface, a main cutting pressure support surface, and a back pressure support surface which include angles smaller than 90° both relative to each other and to a side surface and a frontal surface as the only open side surfaces.

[0003] In use of such tool holders it is extremely important for cutting of work pieces with respect to the accuracy to be achieved in the machining process and especially also to the quality of the surfaces machined for it to be possible to mount the tool holder with its bearing surface absolutely rigid and secure on the base holder by means of the fastening device. In other words, it must be made certain that force components acting between tool holder and base holder as shearing forces or forces of torque, ones which try to twist the tool holder on the base holder, will be introduced safely, that is, without impairing the secure seating, into the base holder by way of the bearing surface.

[0004] DE 195 17 365A1 is a tool holder for machining by turning, comprising a base recess as tool holder which may be mounted with its tool axis oriented so as to be perpendicular to the axis of rotation on a tool carrier as base holder, a cutter holder mounted so as to be replaceable on the base recess, and a cutting plate mounted on the cutter holder so as to be replaceable. The base recess itself has a bearing surface as bearing component extending transversely to the tool axis, the cutter holder having a mounting surface and being detachably mountable with this surface on the bearing surface on the base recess. The cutter holder is immobilized against all relative movements of the mounting surface relative to the bearing surface by means of fitting elements, the cutter holder having at least one cutting insert seat.

[0005] Since in the disclosed solution the bearing component is not configured to be planar but rather is designed with a gear cutting geometry and the mating teeth of tool holder and base holder, the frontal surfaces of which are diametrically opposite each other, despite the fitting elements referred to above, especially ones in the form of set screws, tilting processes occur, something which results in an adverse effect on the accuracy of machining with the indexable inserts seated in the tool holder, since the latter also are also tilted and accordingly displaced in their machining plane. In addition, because of the gear cutting geometries the disclosed solution results in an increased production cost, in particular if the respective toothing is to be produced as high-precision toothing.

[0006] U.S. Pat. No. 5,688,080 discloses a generic tool holder for cutting elements, indexable inserts in particular, a tool holder which may be mounted on a base holder by means of a fastening device with three fastening screws and a bearing component operating in conjunction with this base holder, a bearing component which extends in a planar configuration in the direction of the tool holder, it being possible to introduce the cutting forces generated by the cutting element into the base holder by way of the bearing component, such bearing component of planar configuration being divided by means of a recess which is introduced into planar components between which the recess forms a seat to receive a projecting fitting element of the base holder, and the walls of the recess for the fitting element forming support surfaces which define in relation to each other different planes which, planar in configuration, extend transversely to the bearing component in order thus to introduce into the fitting element of the base holder both the shearing forces resulting from the cutting force and the torsional forces. In the solution as disclosed the recess is, with the exception of an area of opening on an edge in the tool holder, delimited on all sides by three walls which define planes all of which extend perpendicularly to the plane of the planar components so that, in particular with respect to such planar components during fastening of the tool holder to the base holder, over determinations occur which are offset by means of a wedge which may be adjusted by means of a twin screw inside a recess in the fitting element designed to be longitudinally displaceable, a twin screw which thus effects compensation for play between tool holder and base holder. If the bearing play in question is offset in the disclosed solution by way of the wedge, however, this leads to changes in position in the active cutting area of the cutting element, with the result that high-precision machining cannot be carried out with the disclosed solution and this disclosed solution is not cost-effect in production in view of the great variety of components.

[0007] On the basis of this state of the art and the generic tool holder for cutting elements the object of the invention is further to improve the disclosed solutions so that the bearing component is configured so that especially reliable mounting on the base holder is ensured, high-precision machining may be carried out, and production of the tool holder is nevertheless cost effective.

[0008] It is claimed for the invention that this object is attained in that the recess is configured as a channel, four walls delimit the recess and define planes each of which extends perpendicularly to the plane of the planar components, and the two planar components separated from each other by the recess extend in a common plane or in different planes positioned so as to be in parallel with each other. There is hereby obtained a positive locking in position against any movement along the three axes of the three-dimensional coordinates. This positive locking in three different planes, which preferably extend perpendicularly to each other, is obtained without the need for provision of undercut surfaces on the bearing component of the tool holder or on the fitting element of the base holder, so that mounting of the tool holder may be effected by simple insertion of the fitting element into the recess in the course of a rectilinear insertion movement, so that use of the tool holder is made simple and comfortable. In addition, the respective configuration may be accomplished cost-effectively by use of flat bearing and fitting surfaces. In connection with the plane of contact with the seat of the base holder formed by the planar components, which plane of contact in turn is perpendicular to the planes of contact on the support surfaces, there is thus obtained a positive locking, free of play, against movements of translation and rotation relative to all three dimensional coordinate axes. In this regard additional means of compensation for elimination of play, such as the longitudinally adjustable wedge disclosed in U.S. Pat. No. 5,688,080, may be dispensed with in the solution claimed for the invention.

[0009] If the tool holder is provided for use with a base holder forming a beam-like base holder, by preference it is to be possible to mount the tool holder on the latter in such a way that the plane of the bearing component extends in parallel with the primary longitudinal axis of the base holder. In this configuration positive locking of base holder and bearing component prevents torsion about the longitudinal axis of the base holder. In conjunction with the support surfaces formed on the walls of the recess other potential movements within the three-dimensional system of coordinates are eliminated by positive locking.

[0010] By preference the tool holder is in the form of a clamping holder having a clamping jaw integral with a base element, which clamping jaw is mounted on the base element so as to protrude, it being possible to vary the clear span by means of an attachment screw extending through the cutting element for the purpose of clamping this element rigidly in position.

[0011] Preferably clamp bolts which extend through the tool holder in the direction perpendicular to the plane of the bearing surface are provided as fastening device for mounting of the tool holder on the base holder.

[0012] The invention is explained in detail in what follows with reference to an exemplary embodiment illustrated in the drawing, in which

[0013]FIG. 1 presents a perspective view of the exemplary embodiment of the tool holder to be described, as seen in the direction of its bearing component for mounting on a base holder;

[0014]FIG. 2 a detached perspective view of the front part of a base holder designed for seating the tool holder shown in FIG. 1;

[0015]FIG. 3 a partly detached perspective view of the tool holder mounted on the base holder; and

[0016]FIG. 4 a top view of the exemplary embodiment of the tool holder.

[0017] The tool holder claimed for the invention is described in what follows on the basis of an exemplary embodiment, in which the holder is represented by a so-called clamping holder having a base component 1 which has in the area of its front end a seating adapter 3 with a seat as receptacle for a commercially available indexable insert 5. A clamping jaw 7 integral with the base component 1 is mounted on this base component 1 to project in such a way that a clamp opening 9 is formed the clear span of which may be reduced by means of an attachment screw 11 extending through the clamp opening in order to immobilize the indexable insert 5 in its seat in the seating adapter 3 by pressing the clamping jaw 7 against this indexable insert 5.

[0018] As is to be seen in the figures (see FIG. 3 in particular), the opposite wider side of the base component 1 may be mounted on a tool seat 13 of a base holder 15 only the front end area of which with the tool seat 13 is shown in FIGS. 2 and 3. In the part not shown the base holder 15 is in the form of a beam-like support with a primary or longitudinal support axis 17.

[0019] For the purpose of operation in conjunction with the tool seat 13 of the base holder 15 there is, on the associated wider side of the base element 1 of the tool holder as a bearing component, a bearing surface which, as is clearly to be seen in FIG. 1, is divided into two planar components 19 and 21. The two planar components 19 and 21, which together form the bearing component and accordingly the bearing surface, are situated in one common plane. The planar components 19 and 21 are separated by a channel-like recess made in the bearing surface. There is in the seat 13 on the base holder 15 (see FIG. 2) a fitting element 25 in the form of a projection the shape of which is adapted to that of the recess 23 in the base component 1 of the tool holder in such a way that the fitting element 25 may be seated in it. The walls 27, 29, 31, and 33 of the recess 23, which adjoin both the planar component 19 and the planar component 21, each extend perpendicularly to the plane of the bearing surface consisting of the planar components 19 and 21. The walls of the recess 23, which in FIG. 1 are identified as 31 and 33 form support surfaces for positive locking of the tool holder when the latter is mounted on the seat 13 of the base holder 15 so that the fitting element 25 is seated in the recess 23. In this process the wall 31 adjoining the planar component 19 forms a support surface which is adjacent to the front part of the fitting element 25 designated as 37 in FIG. 2, while the wall 33 serves as support surface in conjunction with the upper side, designated as 39 in FIG. 2, of the fitting element 25.

[0020] In the case of the fitting element 25 seated in the recess 23, positive locking by means of adjacent surfaces which extend in several planes which are not parallel to each other on support surfaces which are formed by the planar component 19 of the walls 31 and 33 adjoining the bearing surface of the recess 23. In connection with the plane of contact with the seat 13 of the base holder formed by the planar components 19 and 21, which plane of contact in turn is parallel to the planes of contact on the support surfaces, there is thus obtained a positive locking against movements of translation and rotation relative to all three dimensional coordinate axes.

[0021] In the exemplary embodiment illustrated there are provided for fastening the tool holder on the base holder 15 two clamp bolts 41 which extend through bores in the base component 1 of the tool holder and each of which may be screwed into a bore 43 having internal threading on the seat 13 of the base holder 15. As is to be seen in the figures, one of the clamp bolts 41 extends through the planar surface 19 of the bearing surface of the tool holder, while the other clamp bolt 41 extends inside the recess 23, so that this clamp bolt 41 on the base holder 15 operates in conjunction with a threaded bore 43 which is formed in the fitting element 25.

[0022] Since the walls 27, 29, 31, and 33 extend perpendicularly to the plane of the bearing surface consisting of the planar components 19 and 21, and accordingly the walls of the recess 23 have no undercut, the fitting element 25 may be introduced into the recess 23 with a rectilinear direction of movement when the tool holder is mounted on the base holder 15.

[0023] In the example illustrated the recess 23 is more or less in the form of a channel, so that there is obtained for the fitting element 25 a section designated as 45 in FIG. 2 which extends parallel to the longitudinal axis 17 of the base holder 15. So that, when the tool holder is mounted on the seat 13 a force component which acts in the direction of the arrow 47 in FIG. 1 as a result of tightening of the clamp bolts 41 and as a result tries to displace the longitudinal section 45 of the fitting element 25 along the wall of the recess 23 in order to force the support surface on the wall 31 free of clearance against the part 37 of the fitting element 25, the through bores through which the bolts 41 extend in the base component 1 are displaced minimally relative to the threaded bores 43 on the base holder 15, so that when the bolts 41 are tightened a force component is generated which acts in a direction indicated by the arrow 47 in FIG. 1. The force component acting in this direction also forces the support surface formed on the wall 33 of the planar component against the upper side 39 (FIG. 2) of the fitting element 25 so that there is no clearance.

[0024] In place of the bearing surface extending in one plane as bearing component, this bearing surface may also be configured to be stepped, that is, the planar components 19 and 21 extend in different planes situated parallel to each other. 

1. A tool holder for cutting bodies, indexable inserts (5) in particular, which may be mounted on a base holder (15) by means of a clamping device (41), and a bearing component which extends in the direction of the tool holder in a planar configuration operating in conjunction with the latter, it being possible to introduce the cutting forces generated by way of the bearing component into the base holder (15), the bearing component, designed to be planar, being divided by means of a recess (23) which is introduced into planar components (19 and 21) between which the recess (23) forms a seat to receive a projecting fitting element (25) of the base holder (15), and the walls of the recess (23) forming support surfaces (31 and 33) for the fitting element (25), surfaces each of which defines different planes relative to the others, planes which, planar in configuration, extend transversely to the bearing component in order thus to introduce into the fitting element (25) both the shearing and the torsional forces resulting from the cutting force, characterized in that the recess (23) is configured as a channel, in that two of the walls form a side of the channel and extend in non-parallel planes which extend perpendicularly to the plane of the planar components (19, 21), and in that the two planar components (19, 21) separated from each other by the recess (23) extend in a common plane or in different planes positioned so as to be in parallel with each other.
 2. The tool holder as claimed in claim 1, wherein such tool holder is provided for use with a base holder (15) forming a beam-like support and mountable on such base holder so that the plane of the planar components (19, 21) extends parallel to the primary longitudinal axis of the base holder (15).
 3. The tool holder as claimed in claim 1, wherein at least one first support surface (31) forms a plane which is oriented perpendicular to the primary longitudinal axis (17) defined by the base holder (15) and serves to transmit to the fitting element (25) of the base holder (15) shearing forces resulting from the cutting force and acting in the longitudinal direction.
 4. The tool holder as claimed in claim 3, wherein another support surface (33) which is formed by a wall of the recess (23) adjoining the same planar component (19) of the bearing surface (19 and 21) forms a plane perpendicular to the first support surface (31) and serves to transmit torsional forces resulting from the cutting force to the fitting element (25) of the base holder (15).
 5. The tool holder as claimed in claim 1, wherein such tool holder is configured as a clamping holder and has a clamping jaw (7) integral with a base component (1), which clamping jaw is configured to form a clamp opening (9) projecting from the base component (1), and wherein the clear span of the clamp opening (9) may be reduced for secure clamping of the cutting element (5) by means of an attachment screw (11) extending through such clamp opening.
 6. The tool holder as claimed in claim 1, wherein the fastening device has clamp bolts (41) extending through the tool holder in the perpendicular direction to the plane of the planar components (19, 21) for mounting the tool holder on the base holder (15).
 7. The tool holder as claimed in claim 6, wherein at least one clamp bolt (41) extends through one planar component (19) of the planar component (19, 21) and at least one clamp bolt (41) extends between the planar components (19, 21) of the bearing component through the recess (23) separating such planar components. 